Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 09, 2025 ...

Fuel Tank Temp.

September 04, 2010, 10:21:43 am

Does the 6V92 cool the intake air ( after cooler ) with fuel, is this why the fuel tank get so hot while driving?
Who is the 6V92 Barry Beam?( most knowledgeable )

Quote Selected

Re: Fuel Tank Temp.

Reply #1 – September 04, 2010, 10:42:51 am

The reason the return fuel gets warm/hot on the DDA 6V-92 is simply due to the fuel running thru the engine head(s) and getting hot, then it gets returned to the fuel tank.
This is why some of us install a cooler on the return line.  I use an aux transmission cooler on the return fuel line. Works great in the warm weather, in the winter I remove it.
I am an old time Detroit Diesel fan, meaning I love em even though the newer engines need less playing with.
Enjoy
Dave

Quote Selected

Re: Fuel Tank Temp.

Reply #2 – September 04, 2010, 12:07:42 pm

All diesels use the fuel to cool and lubricate the head and injectors.  So, all heat up the fuel while driving.

I also fit a fuel cooler on the return line (basically, just a high quality medium size Hayden transmission cooler).

Brett Wolfe

Quote Selected

Re: Fuel Tank Temp.

Reply #3 – September 04, 2010, 12:26:43 pm

Brett,  Would having the fuel at a cooler temp as it returns to the pump and injection system cause better mileage ?  What is the advantage of cooling the fuel ?
Gary B

Quote Selected

Re: Fuel Tank Temp.

Reply #4 – September 04, 2010, 12:42:01 pm

More power and perhaps (my speculation) longer life for some engine components that rely on diesel fuel for their cooling and lubrication.  Remember most of these same engines are installed in OTR trucks with large outside mounted saddle tanks.  These outside tanks are better able to dissipate heat than ours that are mounted inside in reasonably insulated compartments.

If you look at the very fine print on any diesel manufacturer's spec sheet for HP and torque, it will mention fuel temperature as one of the parameters that is controlled when generating the HP/torque ratings.

Brett Wolfe

Quote Selected

Re: Fuel Tank Temp.

Reply #5 – September 04, 2010, 01:12:30 pm

To demonstrate how hot fuel can get. On the early 2006 Phenix coaches they did not install a fuel cooler with the then new to Foretravel ISX engine. On my way home with the new coach temps in low 100's the fuel separator which is made of some type of plastic melted until it deformed and fuel started to leak.  I was only up to Dallas so I returned to the factory where they installed a new design cooler.  Never had a problem after that with overheated fuel.  The factory modified all older coaches and made cooler standard on all future coaches.

Quote Selected

Re: Fuel Tank Temp.

Reply #6 – September 05, 2010, 08:59:41 am

Dave, does the 6v92 have an inter/after cooler between the turbo and roots blower to cool the air before going into combustion chamber?
All aircraft engines had a intercooler for this. I read that the 6V92TA, the TA stands for Turbo, Aftercooler.

Quote Selected

Re: Fuel Tank Temp.

Reply #7 – September 05, 2010, 09:26:06 am

Bill, Yes there is a water cooled radiator like plate that fits below the roots blower in the intake,  DDA has some interesting design items such as a bypass blower, that means when the turbo comes up to approx. 5-8 psi boost, the pressure pushes a plunger that unloads the roots  blower adding approx 30hp to output.
If you take a look at your engine, on top toward the bell housing end, you will see a small air hose running  from the airbox to the round vertical plunger housing.  That is the bypass assy. they work great.
Enjoy the 6V-92, a great engine, just use 40wt oil, not 15W-40.
Dave

Quote Selected

Re: Fuel Tank Temp.

Reply #8 – September 05, 2010, 10:11:06 am

Dave, I would like you E-mail address, I like the DDA, but need to know more about it. Cannot find much good info anywhere.
I did not know about bypassing the roots blower!! If you do not mind, I think I have found my "Barry Beam" of the DDA world.

Quote Selected

Re: Fuel Tank Temp.

Reply #9 – September 05, 2010, 09:43:16 pm

Hey guys,
 where are you installing the trans cooler on the fuel line, sounds like a good idea to me
                      thanks
                                  Mitch
ps great forum, I'm learning a lot.

Quote Selected